Electric probing-test machine having a cooling system

Abstract

An electric probing-test machine comprises a probe card having a plurality of probes contacted with chips of a semiconductor wafer and serving to apply test signal to a tester which judges whether circuits on the chips of the wafer are correct or deficient, a main chuck for holding the wafer at a test temperature, a system for cooling the main chuck, and a controller for controlling the cooling system. The main chuck includes a chuck top contacted directly with the wafer, a jacket arranged to conduct heat exchange relative to the chuck top, and a temperature sensor for detecting the temperature of the chuck top. The cooling system has a pump for supplying a coolant from a reservoir to the jacket. Responsive to temperature information detected by the temperature sensor, the amount of the coolant supplied from the reservoir to the jacket is controlled by the controller to thereby control the temperature of the chuck top.

What is claimed is: 
     
       1. An apparatus for cooling a semiconductor wafer comprising: a wafer stage on which a semiconductor wafer is placed;   a heat exchange jacket arranged so as to conduct heat exchange between itself and said wafer stage;   a coolant tank in which a coolant is reserved;   a supply passage communicating said heat exchange jacket and said coolant tank;   a return passage communicating said heat exchange jacket and said coolant tank,   a pair of pump means for circulating the coolant between the coolant tank and the heat exchange jacket via the supply and return passages; and   a bypass for returning the coolant from the supply passage directly tot he coolant tank without passing through the return passage;   wherein the discharge opening of said bypass is positioned above the surface level of the coolant housed in the coolant tank.   
     
     
       2. An apparatus according to claim 1, wherein said pair of pump means includes a supply pump for supplying the coolant from the coolant tank to the heat exchange jacket. 
     
     
       3. An apparatus according to claim 1, wherein said pair of pump means includes a return pump for returning the coolant form the heat exchange jacket to the coolant tank. 
     
     
       4. An apparatus according to claim 1, further comprising a heating coil immersed in the coolant in the collate tank. 
     
     
       5. An apparats according to claim 1, further comprising flow rate adjusting means mounted to said bypass for adjusting the flow rate of the coolant. 
     
     
       6. An apparats according to claim 5, further comprising control means for controlling the flow rate adjusting means based on the flow rate of the coolant within the return passage so as to control the flow rate of the coolant into the bypass.